<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="vue.js"></script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="text" @keyup.20="keyDown" name="" id="">
        <h2 v-show="lbl">当前已切换为大写模式</h2>
    </div>
    <script>
        var app = new Vue({
            el:'#app',
            data: {
                text:'',
                lbl:false
            },
            methods:{
                keyDown() {
                    console.log(1);
                    this.lbl=!this.lbl;
                },
            }
        });

    </script>
</body>

</html>